Fpdf2

Changed
- now `fpdf2` uses the newly supported `DCTDecode` image filter for JPEG images,
instead of `FlateDecode` before, in order to improve the compression ratio without any image quality loss.
On test images, this reduced the size of embeded JPEG images by 90%.
- `FPDF.cell`: the `w` (width) parameter becomes optional, with a default value of `None`, meaning to generate a cell with the size of the text content provided
- the `h` (height) parameter of the `cell`, `multi_cell` & `write` methods gets a default value change, `None`, meaning to use the current font size
- removed the useless `w` & `h` parameters of the `FPDF.text_annotation()` method
Added
- new `FPDF.add_action()` method, documented in the [Annotations section](https://py-pdf.github.io/fpdf2/Annotations.html)
- `FPDF.cell`: new optional `markdown=True` parameter that enables basic Markdown-like styling: `**bold**, __italics__, --underlined--`
- `FPDF.cell`: new optional boolean `center` parameter that positions the cell horizontally
- `FPDF.set_link`: new optional `zoom` parameter that sets the zoom level after following the link.
Currently ignored by Sumatra PDF Reader, but observed by Adobe Acrobat reader.
- `write_html`: now support `align="justify"`
- new method `FPDF.image_filter` to control the image filters used for images
- `FPDF.add_page`: new optional `duration` & `transition` parameters
used for [presentations (documentation page)](https://py-pdf.github.io/fpdf2/Presentations.html)
- extra documentation on [how to configure different page formats for specific pages](https://py-pdf.github.io/fpdf2/PageFormatAndOrientation.html)
- support for Code 39 barcodes in `fpdf.template`, using `type="C39"`
Fixed
- avoid an `Undefined font` error when using `write_html` with unicode bold or italics fonts
Deprecated
- the `FPDF.set_doc_option()` method is deprecated in favour of just setting the `core_fonts_encoding` property
on an instance of `FPDF`
- the `fpdf.SYSTEM_TTFONTS` configurable module constant is now ignored

Fixed
- a bug in the `deprecation` module that prevented to configure `fpdf2` constants at the module level

Fixed
- a "fake duplicates" bug when a `Pillow.Image.Image` was passed to `FPDF.image`

Added
- new features: **document outline & table of contents**! Check out the new dedicated [documentation page](https://py-pdf.github.io/fpdf2/DocumentOutlineAndTableOfContents.html) for more information
- new method `FPDF.text_annotation` to insert... Text Annotations
- `FPDF.image` now also accepts an `io.BytesIO` as input
Fixed
- `write_html`: properly handling `<img>` inside `<td>` & allowing to center them horizontally

Added
- `FPDF.set_xmp_metadata`
- made `<li>` bullets & indentation configurable through class attributes, instance attributes or optional method arguments, _cf._ [`test_customize_ul`](https://github.com/py-pdf/fpdf2/blob/2.3.2/test/html/test_html.py#L242)
Fixed
- `FPDF.multi_cell`: line wrapping with justified content and unicode fonts, _cf._ [118](https://github.com/py-pdf/fpdf2/issues/118)
- `FPDF.multi_cell`: when `ln=3`, automatic page breaks now behave correctly at the bottom of pages

Added
- `FPDF.polyline` & `FPDF.polygon` : new methods added by uovodikiwi - thanks!
- `FPDF.set_margin` : new method to set the document right, left, top & bottom margins to the same value at once
- `FPDF.image` now accepts new optional `title` & `alt_text` parameters defining the image title
and alternative text describing it, for accessibility purposes
- `FPDF.link` now honor its `alt_text` optional parameter and this alternative text describing links
is now properly included in the resulting PDF document
- the document language can be set using `FPDF.set_lang`
Fixed
- `FPDF.unbreakable` so that no extra page jump is performed when `FPDF.multi_cell` is called inside this context
Deprecated
- `fpdf.FPDF_CACHE_MODE` & `fpdf.FPDF_CACHE_DIR` in favor of a configurable new `font_cache_dir` optional argument of the `fpdf.FPDF` constructor